Magnetic transducer and thin-film magnetic head having a stacked structure including an interlayer having a high electrical resistance

Abstract

A magnetic transducer and a thin film magnetic head capable of increasing a resistance change are provided. A spin valve film has a stacked structure comprising a soft magnetic layer, a nonmagnetic layer, a ferromagnetic layer, an antiferromagnetic layer and a protective layer which are stacked in sequence on an underlying layer. Electrical resistance is changed in accordance with a relative angle between the orientation of magnetization of the ferromagnetic layer and the orientation of magnetization of the soft magnetic layer. The ferromagnetic layer includes an inner ferromagnetic layer, a coupling layer and an outer ferromagnetic layer. The inner ferromagnetic layer and the outer ferromagnetic layer are magnetically coupled to each other sandwiching the coupling layer, whereby the magnetizations oriented in opposite directions are generated. A ferromagnetic interlayer having magnetism and the electrical resistance higher than the electrical resistance of the inner ferromagnetic layer is included in the inner ferromagnetic layer closest to the nonmagnetic layer in the ferromagnetic layer. When a current flows through the stack, the ferromagnetic interlayer reflects at least some electrons and limits a route for the electrons and thus a rate of resistance change is increased.

What is claimed is:  
     
       1. A magnetic transducer comprising: 
       a nonmagnetic layer having a pair of facing surfaces;  
       a soft magnetic layer formed on one surface of the nonmagnetic layer;  
       a ferromagnetic layer formed on the other surface of the nonmagnetic layer and capable of having two magnetizations oriented in opposite directions; and  
       an antiferromagnetic layer formed on the ferromagnetic layer on the side opposite to the nonmagnetic layer,  
       wherein the ferromagnetic layer includes a ferromagnetic interlayer having magnetism, and  
       the ferromagnetic interlayer has higher electrical resistance than at least a part of the rest of the ferromagnetic layer, the ferromagnetic interlayer reflecting at least a part of electrons, whereby a route in which the electrons travel is narrowed and the ferromagnetic interlayer containing at least one of oxide, nitride and nitride oxide.  
     
     
       2. A magnetic transducer according to  claim 1 , wherein a distance D 1  between the nonmagnetic layer and the ferromagnetic interlayer is from 1.5 nm to 3 nm inclusive. 
     
     
       3. A magnetic transducer according to  claim 1 , wherein a thickness of the ferromagnetic interlayer is larger than or equal to 0.5 nm and smaller than 1 nm. 
     
     
       4. A magnetic transducer according to  claim 1 , wherein the ferromagnetic layer includes an inner ferromagnetic layer, an outer ferromagnetic layer and a coupling layer sandwiched therebetween, and 
       the inner ferromagnetic layer and the outer ferromagnetic layer are magnetically coupled to each other sandwiching the coupling layer so that the magnetizations thereof may be oriented in opposite directions.  
     
     
       5. A magnetic transducer according to  claim 4 , wherein a relationship between the distance D k1  between the nonmagnetic layer and the ferromagnetic interlayer and a distance D k2  between the ferromagnetic interlayer and the coupling layer of the ferromagnetic layer is defined as 1.2≦D k1 /D k2 ≦3. 
     
     
       6. A magnetic transducer according to  claim 4 , wherein the inner ferromagnetic layer has a first inner ferromagnetic layer and a second inner ferromagnetic layer, and 
       the ferromagnetic interlayer is formed between the first inner ferromagnetic layer and the second inner ferromagnetic layer.  
     
     
       7. A magnetic transducer according to  claim 6 , wherein the first inner ferromagnetic layer, the ferromagnetic interlayer, the second inner ferromagnetic layer, the coupling layer and the outer ferromagnetic layer are arranged in this order on the non magnetic layer. 
     
     
       8. A magnetic transducer according to  claim 6 , wherein the first inner ferromagnetic layer and the second inner ferromagnetic layer have the magnetization oriented in the same direction. 
     
     
       9. A magnetic transducer according to  claim 6 , wherein a relationship between a thickness T ku1  of the first inner ferromagnetic layer of the inner ferromagnetic layer and a thickness T ku1  of the second inner ferromagnetic layer thereof is defined as 1.2≦T ku1 /T ku2 ≦3. 
     
     
       10. A magnetic transducer according to  claim 6 , wherein a relationship between the sum total of the thickness T ku1  of the first inner ferromagnetic layer, the thickness T ku2  of the second inner ferromagnetic layer and a thickness T kn  of the ferromagnetic interlayer, and a thickness T ks  of the outer ferromagnetic layer is defined as 1.2≦(T ku1 +T ku2 +T kn )/T ks ≦3. 
     
     
       11. A magnetic transducer according to  claim 4 , wherein the inner ferromagnetic layer and the outer ferromagnetic layer contain at least one kind of element in a group consisting of nickel (Ni), cobalt (Co) and iron (Fe). 
     
     
       12. A magnetic transducer according to  claim 4 , wherein the coupling layer of the ferromagnetic layer contains at least one kind of element in a group consisting of ruthenium (Ru), rhodium (Rh), rhenium (Re), chromium (Cr) and zirconium (Zr), and 
       the thickness of the coupling layer is from 0.2 nm to 1.2 nm inclusive.  
     
     
       13. A magnetic transducer according to  claim 4 , wherein the ferromagnetic interlayer has some common elements with the inner ferromagnetic layer. 
     
     
       14. A magnetic transducer according to  claim 1 , wherein the antiferromagnetic layer contains at least one kind of element in a group consisting of ruthenium, rhodium, platinum (Pt), palladium (Pd), iron, nickel, cobalt, chromium, iridium (Ir), rhenium and oxygen (O) and manganese(Mn). 
     
     
       15. A magnetic transducer according to  claim 1 , wherein the nonmagnetic layer contains at least one kind of element in a group consisting of gold (Au), silver (Ag) and copper (Cu). 
     
     
       16. A magnetic transducer according to  claim 1 , wherein the soft magnetic layer includes an inner soft magnetic layer, an outer soft magnetic layer and a coupling layer sandwiched therebetween, and 
       the inner soft magnetic layer and the outer soft magnetic layer are magnetically coupled to each other sandwiching the coupling layer so that the magnetizations thereof may be oriented in opposite directions.  
     
     
       17. A magnetic transducer according to  claim 16 , wherein the inner soft magnetic layer has two layers or more differing in material or composition. 
     
     
       18. A magnetic transducer according to  claim 1 , wherein the soft magnetic layer includes a soft magnetic interlayer having magnetism, and 
       the soft magnetic interlayer has higher electrical resistance than at least a part of the rest of the soft magnetic layer.  
     
     
       19. A magnetic transducer according to  claim 18 , wherein a distance D n1  between the nonmagnetic layer and the soft magnetic interlayer is from 1.5 nm to 3 nm inclusive. 
     
     
       20. A magnetic transducer according to  claim 18 , wherein the thickness of the soft magnetic interlayer is from 0.5 nm to 1 nm inclusive. 
     
     
       21. A magnetic transducer according to  claim 18 , wherein the soft magnetic layer includes an inner soft magnetic layer, an outer soft magnetic layer and a coupling layer sandwiched therebetween, and 
       the inner soft magnetic layer and the outer soft magnetic layer are magnetically coupled to each other sandwiching the coupling layer so that the magnetizations thereof may be oriented in opposite directions.  
     
     
       22. A magnetic transducer according to  claim 21 , wherein a distance D n2  between the coupling layer and the soft magnetic interlayer of the soft magnetic layer is from 0.8 nm to 2.0 nm inclusive. 
     
     
       23. A magnetic transducer according to  claim 21 , wherein a relationship between the distance D n1  between the nonmagnetic layer and the soft magnetic interlayer and the distance D n2  between the soft magnetic interlayer and the coupling layer of the soft magnetic layer is defined as 1.2≦D n1 /D n2 ≦3. 
     
     
       24. A magnetic transducer according to  claim 21 , wherein the inner soft magnetic layer has a first inner soft magnetic layer and a second inner soft magnetic layer, and 
       the soft magnetic interlayer is formed between the first inner soft magnetic layer and the second inner soft magnetic layer.  
     
     
       25. A magnetic transducer according to  claim 24 , wherein the first inner soft magnetic layer, the soft magnetic interlayer, the second inner soft magnetic layer, the coupling layer and the outer soft magnetic layer are arranged in this order on the nonmagnetic layer. 
     
     
       26. A magnetic transducer according to  claim 24 , wherein a relationship between the sum total of a thickness T nu1  of the first inner soft magnetic layer, a thickness T nu2  of the second inner soft magnetic layer and a thickness T nn  of the soft magnetic interlayer and a thickness T ns  of the outer soft magnetic layer is defined as 0.35≦T ns /(T nu1 +T nn +T nu2 )≦0.70. 
     
     
       27. A magnetic transducer according to  claim 24 , wherein the first inner soft magnetic layer includes a nonmagnetic-layer-side layer close to the nonmagnetic layer and an interlayer-side layer close to the soft magnetic interlayer. 
     
     
       28. A magnetic transducer according to  claim 27 , wherein the nonmagnetic-layer-side layer contains at least cobalt in a group consisting of nickel, cobalt and iron, and 
       the interlayer-side layer, the second inner soft magnetic layer and the outer soft magnetic layer contain at least nickel in a group consisting of nickel, cobalt, iron, tantalum, chromium, rhodium, molybdenum and niobium.  
     
     
       29. A magnetic transducer according to  claim 21 , wherein the coupling layer included in the soft magnetic layer contains at least one kind of element in a group consisting of ruthenium, rhodium, rhenium, chromium and zirconium, and 
       the thickness of the coupling layer is from 0.2 nm to 1.2 nm inclusive.  
     
     
       30. A magnetic transducer according to  claim 21 , wherein the soft magnetic interlayer has some common elements with the inner soft magnetic layer. 
     
     
       31. A magnetic transducer according to  claim 18 , wherein the soft magnetic interlayer contains at least one of oxide, nitride and nitride oxide. 
     
     
       32. A magnetic transducer comprising: 
       a nonmagnetic layer having a pair of facing surfaces;  
       a soft magnetic layer formed on one surface of the nonmagnetic layer;  
       a ferromagnetic layer formed on the other surface of the nonmagnetic layer; and  
       an antiferromagnetic layer formed on the ferromagnetic layer on the side opposite to the nonmagnetic layer,  
       wherein the ferromagnetic layer has a first ferromagnetic layer, a second ferromagnetic layer, a third ferromagnetic layer, a magnetic interlayer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer, and a nonmagnetic interlayer sandwiched between the second ferromagnetic layer and the third ferromagnetic layer, the magnetic interlayer having higher electrical resistance than that of at least the first ferromagnetic layer, the magnetic interlayer reflecting at least a part of electrons, whereby a route in which the electrons travel is narrowed and the magnetic interlayer containing at least one of oxide, nitride and nitride oxide.  
     
     
       33. A thin film magnetic head having a magnetic transducer, 
       the magnetic transducer comprising:  
       a nonmagnetic layer having a pair of facing surfaces;  
       a soft magnetic layer formed on one surface of the nonmagnetic layer;  
       a ferromagnetic layer formed on the other surface of the nonmagnetic layer and capable of having two magnetizations oriented in opposite directions; and  
       an antiferromagnetic layer formed on the ferromagnetic layer on the side opposite to the nonmagnetic layer,  
       wherein the ferromagnetic layer includes a ferromagnetic interlayer having magnetism, and  
       the ferromagnetic interlayer has higher electrical resistance than at least a part of the rest of the ferromagnetic layer, the ferromagnetic interlayer reflecting at least a part of electrons, whereby a route in which the electrons travel is narrowed and the ferromagnetic interlayer containing at least one of oxide, nitride and nitride oxide.  
     
     
       34. A thin film magnetic head according to  claim 33 , wherein the distance D 1  between the nonmagnetic layer and the ferromagnetic interlayer is from 1.5 nm to 3 nm inclusive. 
     
     
       35. A thin film magnetic head according to  claim 33 , wherein the thickness of the ferromagnetic interlayer is from 0.5 nm to 1 nm inclusive. 
     
     
       36. A thin film magnetic head according to  claim 33 , wherein the ferromagnetic layer includes an inner ferromagnetic layer, an outer ferromagnetic layer and a coupling layer sandwiched therebetween, and 
       the inner ferromagnetic layer and the outer ferromagnetic layer are magnetically coupled to each other sandwiching the coupling layer so that the magnetizations thereof may be oriented in opposite directions.  
     
     
       37. A thin film magnetic head according to  claim 33 , wherein the soft magnetic layer includes an inner soft magnetic layer, an outer soft magnetic layer and a coupling layer sandwiched therebetween, and 
       the inner soft magnetic layer and the outer soft magnetic layer are magnetically coupled to each other through the coupling layer so that the magnetizations thereof may be oriented in opposite directions.  
     
     
       38. A thin film magnetic head according to  claim 33 , wherein the soft magnetic layer includes a soft magnetic interlayer having magnetism, and 
       the soft magnetic interlayer has higher electrical resistance than at least a part of the rest of the soft magnetic layer.  
     
     
       39. A thin film magnetic head having a magnetic transducer, 
       the magnetic transducer comprising:  
       a nonmagnetic layer having a pair of facing surfaces;  
       a soft magnetic layer formed on one surface of the nonmagnetic layer;  
       a ferromagnetic layer formed on the other surface of the nonmagnetic layer; and  
       an antiferromagnetic layer formed on the ferromagnetic layer on the side opposite to the nonmagnetic layer,  
       wherein the ferromagnetic layer has a first ferromagnetic layer, a second ferromagnetic layer, a third ferromagnetic layer, a magnetic interlayer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer, and a nonmagnetic interlayer sandwiched between the second ferromagnetic layer and the third ferromagnetic layer, the magnetic interlayer having higher electrical resistance than that of at least the first ferromagnetic layer, the magnetic interlayer reflecting at least a part of electrons, whereby a route in which the electrons travel is narrowed and the magnetic interlayer containing at least one of oxide, nitride and nitride oxide.